A massive gun battle between rival drug and migrant-trafficking gangs breaks out near the Arizona-Mexico border — raising fears that the escalating violence, like the Monday shooting shown at left, will spill onto American soil.

A massive gun battle between rival drug and migrant trafficking gangs near the U.S. border Thursday left 21 people dead and at least six others wounded, prosecutors said.

HERMOSILLO, Mexico (AP) — A massive gun battle between rival drug and migrant trafficking gangs near the U.S. border Thursday left 21 people dead and at least six others wounded, prosecutors said.

The fire fight occurred in a sparsely populated area about 12 miles (20 kilometers) from the Arizona border, near the city of Nogales, that is considered a prime corridor for immigrant and drug smuggling.

The Sonora state Attorney General’s Office said in a statement that nine people were captured by police at the scene of the shootings, six of whom had been wounded in the confrontation. Eight vehicles and seven weapons were also seized.

All of the victims were believed to be members of the gangs.

The shootings occurred near a dirt road between the hamlets of Tubutama and Saric, in an area often used by traffickers.

Gangs often fight for control of trafficking routes and sometimes steal “shipments” of undocumented migrants from each other, but